Find out why they are in that tree. The presence of Carpenter Ants, or similar species is a symptom of a larger problem, they are not the real problem. Most likely that tree has a rotten spot they are visiting.

From what I have read, these trees give off quite a bit of nectar from the flowers and also out of the leaves and this is what the ants are after. The ants are friend rather than foe because they attack affids

Ants rarely ATTACK aphids, jelymon. They often have a symbiotic (mutualistic) relationship with them, guarding them and protecting them from predators. In return, the ants can harvest the sweet honey-dew that aphids excrete...in sweeter concentrations when stroked by the ants.

Even aggressive southern fire ants will guard aphids (and scale insects) rather than eat them up.